An antibacterial agent is a generic term for antimicrobial agents, and particularly, encompasses substances having antibacterial actions against bacteria, specifically, substances having excellent antibacterial action by inhibiting a bacterial system for synthesizing a cell wall or proteins or products prepared from such substances. Components for an antibacterial agent are mainly extracted from fungi, and have been widely used to treat diseases caused by bacterial infection these days.
Starting with the discovery of the antibacterial agent, penicillin, by Fleming in the 20th century, numerous antibacterial agents and antibiotics have been developed to be free of diseases caused by bacterial infection. These antibacterial agents are an essential part of our life, and have been used in various applications such as food and cosmetic preservatives, as well as medicines. However, in the case of antibacterial agents using chemically synthetic substances, bacteria having resistance to these agents are gradually increasing, and therefore their uses are becoming limited.
Antibacterial agent-resistant bacteria refer to bacteria that have resistance to a specific antibacterial agent and are not affected by a drug action. For example, such bacteria include penicillin-resistant Staphylococcus aureus (S. aureus), which is not affected by the drug action of penicillin at all. In addition, since first reported in the academic world in 1961, it has been reported that methicillin-resistant S. aureus (MRSA) has become a major infectious pathogenic bacterium in the world, vancomycin-resistant Enterococcus (VRE) was first found in Europe in 1988, and vancomycin intermediate-resistant Staphylococcus aureus (VISA) was found in Japan, the US, France and Korea in the late 1990s. In addition, highly vancomycin-resistant S. aureus (VRSA) known as the final agent for treating S. aureus infection, which is the most common causative bacteria of human infection, was first reported in the world by the Centers for Disease Control in the US in 2002, and thus possibility of so-called super bacteria spreading is becoming very high.
Meanwhile, sepsis is an inflammatory response caused by excessively activating the immune system in the body due to a cell wall component, that is, lipopolysaccharide (LPS) acting as a toxin, when the human body is infected by pathogenic gram-negative bacteria, and causes an infection in the entire body or is accompanied by shock when symptoms are severe. Specifically, sepsis is generally caused when immunocompromised hosts with humoral immunodeficiency or cellular immunodeficiency such as patients with underlying diseases such as malignant tumors, leukemia, malignant lymphoma, acquired immunodeficiency syndrome (AIDS), collagen disease, renal failure, liver disease, cerebrovascular disorders, diabetes and the like, the aged or premature infants undergo chemotherapy with an adrenal steroid or antitumor agent, radiotherapy such as cobalt irradiation, or treatment such as an indwelling catheter, blood dialysis, organ transplantation, heart surgery, or the like, or a surgery. Sepsis is the main cause of the death of patients hospitalized in an intensive care unit, and a very serious disease generally having a mortality rate of 30% or more. Despite the advances in medical technology, in many cases, sepsis is still caused globally by infection following surgery, and when people with weak immune systems such as infants or the aged are infected, they often develop sepsis in many cases. Representatively, neonatal sepsis is known to occur in approximately 3 out of 1,000 full-term infants, and known to increase by 3 to 4 times in premature infants. When a person develops sepsis, the patient generally undergoes treatment with an antibiotic, but effective treatment may not be achieved only with the antibiotic when bacteria are highly proliferated due to a delay in suitable treatment or infection was made by a strain with strong resistance against antibiotics. Therefore, since pathogenic bacteria having resistance against various antibiotics are gradually increasing, the development of a novel agent for treating sepsis is urgent.
Therefore, the inventors had attempted to develop a novel antibacterial agent and an agent for treating sepsis, thereby confirming that a Mycobacterium tuberculosis-derived ADK protein has excellent antibacterial activity selectively against gram-negative bacteria, has excellent effects of inhibiting bacterial proliferation and eliminating endotoxins isolated from dead bacteria, thereby minimizing side effects caused by antibiotics when used in combination with an antibiotic, and has a significantly excellent effect of treating sepsis, compared to single administration, and thus completed the present invention.